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Mathematics

The mean of given data is 26.

C.I.0 - 2020 - 4040 - 60
f20x10

Statement (1): x = 26.

Statement (2): 26 = 10×20+30×x+50×1030+x\dfrac{10 \times 20 + 30 \times x + 50 \times 10}{30 + x}.

  1. Both the statement are true.

  2. Both the statement are false.

  3. Statement 1 is true, and statement 2 is false.

  4. Statement 1 is false, and statement 2 is true.

Measures of Central Tendency

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Answer

Given:

C.I.fx(Midpoint) = (Lower limit + upper limit)/2
0-202010
20-40x30
40-601050

By formula; Mean = f.xf\dfrac{∑f.x}{∑f}

Substituting the values, we get

26=20×10+x×30+10×50x+30So, statement 2 is true.26=200+30x+50030+x26(30+x)=200+30x+500780+26x=700+30x30x26x=7807004x=80x=804x=20\Rightarrow 26 = \dfrac{20 \times 10 + x \times 30 + 10 \times 50}{x + 30}\\[1em] \text{So, statement 2 is true.}\\[1em] \Rightarrow 26 = \dfrac{200 + 30x + 500}{30 + x}\\[1em] \Rightarrow 26(30 + x) = 200 + 30x + 500\\[1em] \Rightarrow 780 + 26x = 700 + 30x\\[1em] \Rightarrow 30x - 26x = 780 - 700\\[1em] \Rightarrow 4x = 80 \\[1em] \Rightarrow x = \dfrac{80}{4} \\[1em] \Rightarrow x = 20

∴ Statement 1 is false, and statement 2 is true.

Hence, option 4 is the correct option.

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